Control of flue gas-air system for fired heaters based on steady state model
ZHANG Wei-yong1, LI Ying1, HUANG De-xian1， YI Jia2 ZHANG Zhi-yin2, YANG Xiang-dang2
1. Department of Automation, Tsinghua National Laboratory for Information Science and Technology, Tsinghua University, Beijing 100084, China; 2. Huabei Petrochemical Company PetroChina, Renqiu 062552, China
Due to the difficulties in the control of flue gas-air system of fired heater, such as severe nonlinearities, low sensitiveness to control signal which exists widely in the actuators, and high coupling of process variables, it’s not easy to guarantee stability and safety by the dynamic control method. A control strategy adopting steady state model was proposed. The steady state model directly calculates the control move and implements it. Then the controller waits one settling time, and the next control move is calculated using the steady state feedback information if necessary. A sufficient condition for convergence was proved. The method avoids the potential dangerous caused by high frequency adjustment and provides stable control. Automatic control for the whole fired heater unit was achieved by applying the control strategy to the chamber oxygen content and pressure control. Simulation and industrial application show that the control performance is satisfactory. The strategy provides a basis for safe and smooth operation, and further thermal efficiency optimization.
ZHANG Wei-yong, LI Ying, HUANG De-xian, YI Jia,ZHANG Zhi-yin, YANG Xiang-dang. Control of flue gas-air system for fired heaters based on steady state model. J4, 2011, 45(12): 2093-2098.
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